Increase of the Ventilation Effectiveness of Solar Chimneys with Consideration of Wind-Effects Applying CFD Simulations and Measurements
Abstract
Solar chimneys have been used for natural ventilation and cooling in the Middle East already hundreds of years ago. In modern buildings, the concept could contribute to energy savings and reduction of greenhouse gas emissions. An optimized system would enable a sustainable and permanent operation of this natural ventilation concept. This study analyzes the effect of wind and the possibilities to increase the ventilation effectiveness of solar chimneys by optimizing the design of the chimney outlet. Computational fluid dynamic (CFD) simulations have been used to investigate the general influence of the wind effects on a building which is naturally ventilated with solar chimneys. The results show that the air change rate increases or decreases depending on the predominating wind direction. To be able to accomplish a system which supports the natural ventilation irrespective of the wind direction, different wind cowls were tested at a test rig located at the University of Applied Sciences Munich. As a result of this study, the flow velocity can be shown as a square root function of the wind speed. An average flow velocity between 0.6 – 1.1 m/s can be reached by using turbine ventilation systems.